cognomen
UK: /kɒɡˈnəʊmən/ | US: /kɑːɡˈnoʊmən/
n. a surname or family name, especially in ancient Rome
n. a nickname or distinguishing name
n. (biology) the third part of a scientific name in binomial nomenclature
Derived from Latin cognōmen, combining co- (a variant of com-, meaning "with/together") and nōmen ("name"). In ancient Rome, it originally referred to an additional personal name distinguishing individuals within a family (e.g., "Caesar" in "Gaius Julius Caesar"). Over time, it broadened to denote nicknames or scientific naming conventions. The morpheme nomen persists in English (e.g., "nominate," "nomenclature"), while cog- appears in words like "cognate" (shared linguistic origin).
In Roman society, a cognomen often reflected a person’s achievements or traits.
"Ironside" was a cognomen given to the fearless warrior.
The biologist noted the cognomen in the species’ Latin classification.
His sharp wit earned him the cognomen "the Thinker."
Unlike the praenomen, the cognomen was not limited to a fixed list of names.